I recently started buying GFUEL to help me through my 14hr shifts at work. Maybe it works? Maybe it's just a placebo effect? Either way, I'm smashing through the day and not feeling tired at all! So I'd happily pay for a placebo if it works and I'm more than happy to pay for it if it genuinely works!
As for flavour... I've tried a few and so far SOUR BLUE CHUG RUG is the one for me!
I've recently bought a couple of different flavours to try once the SBCR is all gone and I can't wait to see what they're like.
I'd definitely suggest trying GFUEL at least once and they even sell little sample packs on their site if you don't wanna spend loads on a whole tub you might end up throwing away.